Band clamps are widely used in a variety of applications. Band clamps generally include a band which is formed into a loop around an object, such as a pole or other object, and a buckle that receives the opposing end of the band. The band and buckle cooperate to lock the band in a fixed position relative to the buckle. Tools are employed to tighten the band around one or more objects, secure or lock a free end of the band relative to a buckle or locking member, and cut any excess portion of the band. Typically, these tools grasp the free end of the band after it has passed through the buckle and apply a force to the free end of the band while simultaneously maintaining the position of the buckle to tighten the band around one or more objects. Once an appropriate tension is applied to the band, the tool will create the desired locking geometry in the band and/or buckle and shear the portion of the free end of the band extending beyond the buckle. Typically, a blade performs the shearing or cutting operation.
Tools that perform the tightening, locking and cutting functions are primarily manual, pneumatic or electric in nature. In the case of pneumatic or electric tools, limited or reduced physical effort is required by the operator as compared to most manual tools. Band tightening tools that are pneumatic or electric are usually semiautomatic in that the operator of such a tool is required to perform some, but not all, of the tasks or functions associated with providing a band clamp about an object. Manual tasks that remain may include locating the band, or tie as it is sometimes called, about the object and inserting or otherwise locating the band clamp relative to the tool so that the tool can perform one or more of its tightening, locking and cutting functions.
Band clamps of the prior art have certain drawbacks. For example, there is a need for improving loop tensile force (the force required to break the band or the lock) other than by simply increasing the physical size of the band and buckle. Also, there is a need for improving the percentage of retained force (the residual force in the band after forming the lock). Stated differently, there is a need to reduce or eliminate the tensile load that is lost following formation of the lock and release of the band by the tool. For a number of reasons, including tolerances and imprecise metal forming techniques, once the tool cuts the free end of the band, a portion of the band tends to slip back through the buckle expanding the circumference of the band. As a result, a portion of the retained tensile load is lost and the percent retained force decreases. The formed lock may also relax or loosen over time, causing the band circumference to expand, particularly if the outward force applied on the band by the constrained objects is large or if the band and buckle are subjected to external forces such as vibration or other motion causing relative motion of the band and buckle. Still further, there is a need in some applications to increase the clamping force (the maximum force reached just prior to the band tightening tool cutting off the excess end of the band). The clamping force is related to the retained force. Typically, the higher the clamping force, the higher the retained force.
In addition to the foregoing problems, other considerations are relevant in designing a band clamp. First, the band clamp should have a high tensile strength to resist the outward tensile force exerted thereon by the constrained object or objects. Second, the band clamp should be inexpensive to manufacture. Band clamps are used in a variety of applications where cost is a concern. Thus, simply increasing the physical size of the band clamp does not address all of the design considerations, including cost constrictions. A physically larger band clamp will have a greater loop tensile force, but it will cost more. In addition, the band clamp should be simple in design and easy to use.